What Kind of Bug Is This? Common Bug Groups

Is It a Grub? How to Tell Grubs From Look-Alikes

Grubs: 5 marks to check, what they are often confused with, whether they bite or sting, and where they turn up, quoted from university entomology and IPM sources.

These pages help you narrow a bug down to its group from what you can see. They are not medical advice. Seek medical care promptly for severe symptoms or any sign of an allergic reaction.

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At a glance

Group: Grubs are the larval (immature) life stage of scarab beetles (order Coleoptera), e.g., masked chafers and June beetles — not a taxonomic group of their own.
Body plan: White grubs are white, C-shaped larvae with dark head capsules; species such as masked chafer larvae have three pairs of true legs (six legs total) near the front of the body; some other soil-dwelling larvae (e.g., billbug larvae) lack legs entirely. Adult length ranges roughly 1/4 inch to 2 inches depending on species.
Size: White grub larvae range from about 1/4 inch to 2 inches long depending on species (e.g., masked chafer about 1 inch, billbug about 3/8 inch).
Bites or stings: Not covered by the sources we opened; handle unknown bugs with care.
Where you find them: White grubs occur in compost piles, lawns, garden beds, and landscape beds near grassy areas or areas recently converted from grass.

How to tell it is one of the grubs

Grubs are beetle (Coleoptera) larvae, distinguished from caterpillars, sawfly larvae, and fly larvae by the number/arrangement of prolegs and presence of true legs.
Beetle larvae (grubs) have true legs but no prolegs — this is the key difference from caterpillars.
Caterpillars have proleg pairs on five or fewer abdominal segments plus three pairs of true legs, unlike legless-proleg grubs.
Fly larvae (maggots) lack true legs entirely, unlike grubs which retain three pairs of true legs.
Species vary even among true white grubs: masked chafer larvae (1 inch, dark head, six legs) versus billbug larvae (3/8 inch, dark head, white body, no legs).

Often confused with

People most often mix grubs up with:

Open the other page and compare its list against the marks above; the differences are usually in the antennae, wings or the way the body is divided.

Pest or beneficial?

Not all white grub species cause damage; grass-root-feeding species can become lawn pests in high numbers, but low populations (about 6 or fewer per square foot) are generally tolerable and treatment is often unnecessary.

Where they turn up

White grubs occur in compost piles, lawns, garden beds, and landscape beds near grassy areas or areas recently converted from grass.

How to photograph it for identification

Get as close as your camera will focus, from directly above, in daylight or a bright lamp. Include the whole body with the legs and antennae in frame; a second shot from the side shows wings and body segments. Put a coin or ruler next to it for scale. For a bite or a bug found on skin or bedding, photograph the bug itself, not the mark. The app names the likely group; use the list above to confirm.

FAQ

Do grubs bite or sting?

The sources we opened for this group do not describe bites or stings. Treat any bug you cannot identify with care and avoid handling it bare-handed.

What is the quickest way to recognize grubs?

Grubs are beetle (Coleoptera) larvae, distinguished from caterpillars, sawfly larvae, and fly larvae by the number/arrangement of prolegs and presence of true legs.

Are grubs a pest?

How do I tell grubs from caterpillars?

Beetle larvae (grubs) have true legs but no prolegs — this is the key difference from caterpillars. Caterpillars have proleg pairs on five or fewer abdominal segments plus three pairs of true legs, unlike legless-proleg grubs. Fly larvae (maggots) lack true legs entirely, unlike grubs which retain three pairs of true legs. Species vary even among true white grubs: masked chafer larvae (1 inch, dark head, six legs) versus billbug larvae (3/8 inch, dark head, white body, no legs). The Caterpillars page lists its own marks.

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